This study seeks to quantify Interleukin-8 (IL-8) levels in the sputum and plasma of patients hospitalized with cystic fibrosis. IL-8 levels will be obtained in these patients at the initiation of hospitalization and after one and two weeks of treatment with intravenous antibiotics and other therapeutic modalities. IL-8 levels will be correlated with clinical status as determined by NIH scoring, including pulmonary function testing and chest x-ray scoring.